Filament lamp with reflector

Abstract

The invention provides a lighting device (10) comprising (i) a plurality of elongated filaments (100) and (ii) an optical element (200), wherein: —each elongated filament (100) comprises a support (105) and a plurality of solid state light sources (110), wherein the elongated filament (100) has a first axis of elongation (120) having a first length (L1), wherein the elongated filament (100) is configured to generate filament light (101) over at least part of the first length (L1); and—the optical element (200) comprises a plurality of facets (210), wherein the optical element (200) has a second axis of elongation (220) having a second length (L2), wherein the optical element (200) has a non-circular cross-section perpendicular to the second axis of elongation (220), wherein the optical element (200) is configured between at least two of the plurality of elongated filaments (100), and wherein the optical element (200) is configured to redirect at least part of the filament light (101).

The invention claimed is: 
     
       1. A lighting device comprising (i) a plurality of elongated filaments and (ii) an optical element, wherein:
 each elongated filament comprises a support and a plurality of solid state light sources, wherein the elongated filament has a first axis of elongation having a first length, wherein the elongated filament is configured to generate filament light over at least part of the first length; and 
 the optical element comprises a plurality of facets, wherein the optical element has a second axis of elongation having a second length, wherein the optical element has a non-circular cross-section perpendicular to the second axis of elongation, wherein the optical element is configured between at least two of the plurality of elongated filaments, and wherein the optical element is configured to redirect at least part of the filament light, 
 wherein the optical element comprises one or more optical element units, wherein each optical element unit comprises one or more of the plurality of facets, wherein the one or more facets of the optical element unit are symmetrically configured relative to the second axis of elongation, and wherein the one or more facets of the optical element unit taper in a direction parallel to the axis of elongation and, 
 the lighting device further comprising one or more sets, wherein each set comprises two adjacently configured optical element units, wherein the optical element units within the set taper in opposite directions. 
 
     
     
       2. The lighting device according to  claim 1 , wherein the optical element is configured to redirect at least part of the filament light by one or more of reflection at a facet and refraction at facets. 
     
     
       3. The lighting device according to  claim 1 , wherein the optical element is configured to redirect at least part of the filament light by diffuse reflection. 
     
     
       4. The lighting device according to  claim 1 , wherein the optical element comprises one or more optical element units, wherein each optical element unit comprises one or more of the plurality of facets, wherein for one or more of the facets of the optical element unit applies that a facet normal configured perpendicular to the facet complies with one of the conditions selected from (i) the facet normal does not intersect with an adjacent elongated filament, and (ii) the facet normal and the axis of elongation of an adjacent elongated filament have a mutual angle (β 1 ) unequal to 90°. 
     
     
       5. The lighting device according to  claim 4 , wherein the first axes of elongation of the respective elongated filaments are configured parallel to the second axis of elongation. 
     
     
       6. The lighting device according to  claim 1 , wherein the elongated filament comprises luminescent material configured to convert at least part of the solid state light source light into luminescent material light, and wherein the filament light comprises the luminescent material light and optionally the solid state light source light. 
     
     
       7. The lighting device according to  claim 6 , wherein the filament light is generated essentially 360° around the axis of elongation. 
     
     
       8. The lighting device according to  claim 6 , comprising a plurality of the sets. 
     
     
       9. The lighting device according to  claim 1 , wherein the optical element comprises one or more optical element units, wherein each optical element unit comprises two or more of the plurality of facets, wherein two or more of the two or more facets circumferentially surround the second axis of elongation, wherein adjacent facets define a facet edge. 
     
     
       10. The lighting device according to  claim 9 , wherein one or more of the one or more optical element units each comprise 3-12 facets. 
     
     
       11. The lighting device according to  claim 9 , wherein one or more of the facet edges, one or more of the first axes of elongation, and the second axis of elongation, are configured in a plane. 
     
     
       12. The lighting device according to  claim 1 , wherein one or more of the plurality of first axes of elongation are slanted relative to the second axis of elongation. 
     
     
       13. The lighting device according to  claim 1 , wherein one or more of the facets are concave. 
     
     
       14. The lighting device according to  claim 1 , wherein one or more of the plurality of elongated filaments is configured to provide more filament light in the direction of the optical element than in opposite directions. 
     
     
       15. The lighting device according to  claim 1 , comprising (i) a base, and (ii) an outer bulb, together defining an enclosure enclosing the plurality of elongated filaments and the optical element, wherein the solid state light sources comprise LEDs, and wherein the elongated filaments are straight elongated elements.